Karen Khachanov, of the Russian Olympic Committee, wipes his face during the men's single gold medal match of the tennis competition against Alexander Zverev, of Germany, at the 2020 Summer Olympics, Sunday, Aug. 1, 2021, in Tokyo, Japan. (AP Photo/Patrick Semansky)

during the men's single gold medal match of the tennis competition at the 2020 Summer Olympics, Sunday, Aug. 1, 2021, in Tokyo, Japan. (AP Photo/Patrick Semansky)

Alexander Zverev, of Germany, serves to Karen Khachanov, of the Russian Olympic Committee, during the men's single gold medal match of the tennis competition at the 2020 Summer Olympics, Sunday, Aug. 1, 2021, in Tokyo, Japan. (AP Photo/Patrick Semansky)

Alexander Zverev, of Germany, reacts after winning the men's single gold medal match of the tennis competition against Karen Khachanov, of the Russian Olympic Committee, at the 2020 Summer Olympics, Sunday, Aug. 1, 2021, in Tokyo, Japan. (AP Photo/Patrick Semansky)

Alexander Zverev, of Germany, returns a shot to Karen Khachanov, of the Russian Olympic Committee, during the men's single gold medal match of the tennis competition at the 2020 Summer Olympics, Sunday, Aug. 1, 2021, in Tokyo, Japan. (AP Photo/Patrick Semansky)

Alexander Zverev, of Germany, reacts after winning the men's single gold medal match of the tennis competition against Karen Khachanov, of the Russian Olympic Committee, at the 2020 Summer Olympics, Sunday, Aug. 1, 2021, in Tokyo, Japan. (AP Photo/Patrick Semansky)

Alexander Zverev, of Germany, returns a shot to Karen Khachanov, of the Russian Olympic Committee, during the men's single gold medal match of the tennis competition at the 2020 Summer Olympics, Sunday, Aug. 1, 2021, in Tokyo, Japan. (AP Photo/Seth Wenig)

International Olympic Committee President Thomas Bach, left, speaks with guest during the men's single gold medal match of the tennis competition at the 2020 Summer Olympics, Sunday, Aug. 1, 2021, in Tokyo, Japan. (AP Photo/Patrick Semansky)

Anastasia Pavlyuchenkova and Andrey Rublev, of the Russian Olympic Committee, react to a point during the mixed doubles gold medal match of the tennis competition at the 2020 Summer Olympics, Sunday, Aug. 1, 2021, in Tokyo, Japan. (AP Photo/Seth Wenig)